I see that they are an OEM manufacturer. Based on the sales locations described, they are sold by high end design studios. I would refer to them as a "boutique" company, but from the Website, it looks like they are international and a large company. Nonetheless, the same could have been said for Broadway Faucets, and people who purchased them ( paid huge $$$$ for them!) are now up a creek.
Without any further knowledge, I would go to the largest plumbing supplier in your region. Ask if they stock, or know how to obtain, repair parts for the Graff brand. Then ask the company you are buying from what their warranty policy is and if they assist in getting repairs done. Finally, contact Graff ( www.graff-faucets.com) and ask them about warranties and parts down the line.
They are probably great faucets. I would like to know what you are paying for one. You will find that most plumbers here on the forums always recommend the mainstream brands. This is because it is a known quantity. We know how to put them together and take them apart. Because of the huge population of Deltas, PP, AmStd, Moen...... parts are widely available, even at the corner hardware store or the box stores. We probably have the part you need ON THE TRUCK....so you aren't paying labor cost for a parts run, and don't have to be without a faucet for 5 to 20 days while parts are ordered.
If the Mrs. has fallen in love with a faucet, there's no going back! My personal advice is always to buy 2.......the second one will be your parts supply.